Like any other skilled activity, speech production requires the intricate coordination of several different subsystems. For speech, these subsystems are the respiratory system, the larynx, and the different parts of the supralaryngeal vocal tract. Our proposed experiments will help to uncover the nature of this coordination, both within and across these subsystems, through careful and detailed observations of articulator movements using state-of-the-art technologies. We will address the problem of coordination and sequencing of articulatory movements by instructed variation of phonetic context, stress, and prosody. These experimental manipulations will enable us to examine how relatively constant communicative ends are achieved by different means in speech. That is, even in the face of these linguistic/performance variations, the acoustic signal must stay within certain limits given its' status as a vehicle for transmitting messages. The proposed experiments will study, in populations of normal adult speakers, the control of oral closure and constriction for stops and fricatives in a wide variety of segmental and suprasegmental contexts. The kinematics of tongue movements used for shaping the vocal tract in the production of diphthongs will be examined to collect baseline data, since there is virtually no articulatory data on these sounds. The experiments will also examine the temporal coordination of the lips and the tongue, and how their kinematics and timing are affected by phonetic context. Together, the results of these experiments will contribute important articulatory data from several speakers. Such data are not only necessary for the development of computational models of the vocal tract, but will also serve as references for comparison with the speech of disordered populations.